1) Field of the Invention
The invention herein relates to an improved structure tape rule, specifically an original structural arrangement in which the blade spool has space at one side of one-piece construction for containing the coiled spring, enabling the blade spool to accommodate the winding of a ruler blade that is approximately two to three times longer than a blade spool in a same diameter size spatial area and, furthermore, the rewinding of the ruler blade is impelled by spring torque to thereby enhance tape ruler utility and performance.
2) Description of the Prior Art
A conventional tape rule utilizing an internal blade spool consists of a concentric spring at the center and a ruler blade wound around the exterior, a hook riveted to the front end of the ruler blade, and a center shaft projecting from the inner side of a left case half for inserting the center section of the spring in the blade spool; screws are respectively inserted through mounting holes in the right case half on the other side and fastened to the center shaft and mounting posts of the left case half to thereby assemble the said tape rule. Given the structure of the conventional tape rule, since there is a concentric spring coiled in the said blade spool, the said spring occupies space at the center of the blade spool and the remaining space can only be used for winding the tape ruler blade, a conventional tape ruler blade has a length of approximately five meters; furthermore, extending the length of the tape ruler blade requires an increase in the diameter of the blade spool and, at the same time, when the tape ruler blade is utilized for measurements and pulled out longer distances, the rewinding torque of the spring must be considered in that additional space will be needed to fit a stronger spring; however, to meet ergonomic concerns, since the maximum dimensions of the tape rule housing is limited to what the average hand is capable of grasping, increasing the diameter of the blade spool is difficult. As a result, to facilitate tape rule usage, the applicant of the invention herein conducted extensive research and development based on many years of specialized production experience to further enhance the practical value of the invention herein which following repeated testing and refinement culminated in the improved tape rule structure of the present invention.